Tracking apparatus

ABSTRACT

A tracking apparatus includes a grouping setting unit, a tracking feature detection unit, a tracking unit. The grouping setting unit groups a plurality of focus detection areas with an in-focus state. The tracking feature detection unit detects a feature amount of the tracking target in areas of the groups grouped. The tracking unit tracks the tracking target in accordance with a first or second tracking position depending on the number of the set groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/052,311, filed Oct. 11, 2013, which claims the benefit of priorJapanese Patent application Ser. No. 2012-227758, filed Oct. 15, 2012,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tracking apparatus which is appliedto an imaging device such as a digital camera and which improves theperformance of tracking a tracking target subject.

2. Description of the Related Art

Techniques for tracking a subject are known in, for example, Jpn. Pat.Appln. KOKAI Publication No. 2007-011054 and Jpn. Pat. Appln. KOKAIPublication No. 2009-268086. Jpn. Pat. Appln. KOKAI Publication No.2007-011054 discloses the use of, for example, an AF evaluation valueused in contrast autofocus (contrast AF) to track a subject. Accordingto the disclosure in this publication, an autofocus lens is driven, andat the same time, a contrast detection signal are calculated regarding aplurality of AF areas in accordance with an output signal of an imagepickup device. The movement of the subject between the AF areas isdetected from the calculated contrast detection signal. An in-focusposition is found in accordance with the detection result.

Jpn. Pat. Appln. KOKAI Publication No. 2009-268086 discloses tracking asubject by using at least two regions for tracking the subject.According to the disclosure in this publication, a first region and asecond region for tracking the subject are provided on image dataacquired by imaging the subject. The first region is always used as astandard region to track the subject. The second region is usedindependently of the first region to track the subject.

The tracking process is briefly described for reference. FIG. 21 showsan example of a frame image for a given timing in tracking operation.FIG. 22 shows an example of a frame image taken one frame later in thetracking operation. In an imaging screen 1 of a digital camera, asubject (subject to be tracked) A such as a person to be tracked exists,and a tracking frame W for tracking the subject A is displayed at atracking position B1. A plurality of two-dimensionally arranged focusdetection areas C are shown in the imaging screen 1. These focusdetection areas C detect the in-focus state regarding the subject A.These focus detection areas C correspond to a plurality oftwo-dimensionally arranged focus detecting pixels in an image pickupdevice having a plurality of two-dimensionally arranged pixels, forexample, in the digital camera.

The tracking frame W is set in accordance with the size of the subjectA. In the tracking frame W, the number of the focus detection areas Cused to track the subject A varies by the size of the tracking frame W.For example, in the frame image shown in FIG. 21, the tracking frame Whas a size corresponding to the size of the tracking frame W. Forexample, ten focus detection areas C are included in the tracking frameW in accordance with the size of the tracking frame W. In the frameimage taken one frame later shown in FIG. 22, the tracking frame Wtracks the subject A moving rightward, and moves in the same rightwarddirection to reach a tracking position B1. The size of the trackingframe W does not change with tracking, and the number of the focusdetection areas C included in the tracking frame W remains ten.

BRIEF SUMMARY OF THE INVENTION

A tracking apparatus according to an aspect of the present inventioncomprises: a grouping setting unit which groups a plurality of focusdetection areas in accordance with an in-focus state among the focusdetection areas in image data including a tracking target; a trackingfeature detection unit which detects a feature amount of the trackingtarget in areas of the groups grouped by the grouping setting unit; anda tracking unit which sets the focus detection area focused on thetracking target as a first tracking position, sets a part having thefeature amount detected by the tracking feature detection unit as asecond tracking position, and tracks the tracking target in accordancewith the first or second tracking position depending on the number ofthe set groups.

A tracking method according to an aspect of the present inventioncomprises: grouping a plurality of focus detection areas in accordancewith an in-focus state among the focus detection areas in image dataincluding a tracking target; detecting a feature amount of the trackingtarget in an area of the set group; setting the focus detection areafocused on the tracking target as a first tracking position; setting apart having the feature amount of the tracking target as a secondtracking position; and tracking the tracking target in accordance withthe first or second tracking position depending on the number of the setgroups.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a configuration diagram showing one embodiment of an imagingdevice comprising a tracking apparatus according to the presentinvention;

FIG. 2 is a diagram showing how focus detection areas are grouped inaccordance with an in-focus state by a grouping setting circuit in thetracking apparatus;

FIG. 3 is a diagram showing the operation of specific grouping by thegrouping setting circuit in the tracking apparatus;

FIG. 4 is a diagram showing the operation of the specific grouping bythe grouping setting circuit in the tracking apparatus;

FIG. 5A is a diagram illustrating how the face of a subject is detectedfrom image data by a face detection processing circuit in the trackingapparatus;

FIG. 5B is a diagram illustrating how the face of a subject is detectedfrom image data by a face detection processing circuit in the trackingapparatus;

FIG. 6A is a diagram illustrating the function of tracking usingluminance information by a luminance tracking processing circuit in thetracking apparatus;

FIG. 6B is a diagram illustrating the function of tracking usingluminance information by a luminance tracking processing circuit in thetracking apparatus;

FIG. 7A is a diagram illustrating the function of tracking using colorinformation by a color information tracking processing circuit in thetracking apparatus;

FIG. 7B is a diagram illustrating the function of tracking using colorinformation by a color information tracking processing circuit in thetracking apparatus;

FIG. 8 is an imaging operation flowchart in the tracking apparatus;

FIG. 9 is a diagram showing a tracking frame displayed on the facedetected by the face detection processing circuit in the trackingapparatus;

FIG. 10 is a diagram showing the tracking frame displayed on the facedetected by the face detection processing circuit in the trackingapparatus;

FIG. 11 is a tracking process flowchart in the tracking apparatus;

FIG. 12 is a diagram showing a release AF in-focus area in a release AFprocess in the tracking apparatus;

FIG. 13 is a diagram showing a luminance/color information tracking areain which the subject is tracked by a tracking feature detection circuitin the tracking apparatus;

FIG. 14A is a first tracking process flowchart in the trackingapparatus;

FIG. 14B is a first tracking process flowchart in the trackingapparatus;

FIG. 15 is a priority tracking position determination flowchart in thetracking apparatus;

FIG. 16 is a composition showing a case in which one focus detectionarea group is provided for the subject in a priority tracking positiondetermination in the tracking apparatus;

FIG. 17 is a composition showing a case in which one focus detectionarea group is provided when two subjects are located close to each otherin the priority tracking position determination in the trackingapparatus;

FIG. 18 is a composition showing a case in which two focus detectionarea groups are provided when two subjects are located apart from eachother in the priority tracking position determination in the trackingapparatus;

FIG. 19 is a diagram illustrating tracking operation in which a vehiclecomes into a composition for photographing the subject in the trackingapparatus;

FIG. 20 is a diagram showing a tracking result in which the vehiclecomes into the composition for photographing the subject in the trackingapparatus;

FIG. 21 is a diagram illustrating a background art for tracking;

FIG. 22 is a diagram illustrating the background art;

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings.

FIG. 1 shows an example of a configuration diagram of an imaging device100 comprising a tracking apparatus. The imaging device (main device)100 comprises a photographic optical system 102, a focus adjustmentmechanism 104, a diaphragm 106, a diaphragm driving mechanism 108, ashutter 110, a shutter driving mechanism 112, an imaging element 114, animaging element interface (IF) circuit 116, an SDRAM 118, a displayelement 120, a display element driving circuit 122, a touch panel 124, atouch panel driving circuit 126, a recording medium 128, a systemcontroller 130 equipped with a CPU 1301, a camera operation switch 132,and a flash ROM 134.

An imaging section 101 includes the photographic optical system 102, thefocus adjustment mechanism 104, the diaphragm 106, the diaphragm drivingmechanism 108, the shutter 110, the shutter driving mechanism 112, theimaging element 114, and the imaging element interface (IF) circuit 116.

The photographic optical system 102 focuses a light flux F from asubject on a light receiving surface of the imaging element 114. Thephotographic optical system 102 includes a plurality of lenses such as afocus lens. The focus adjustment mechanism 104 includes a motor and adriving circuit for the motor. The focus adjustment mechanism 104 drivesthe focus lens in the photographic optical system 102 in its opticalaxis direction (chain line direction shown) under the control of the CPU1301.

The diaphragm 106 is configured to open/close, and adjusts the amount ofthe light flux F entering the imaging element 114 via the photographicoptical system 102. The diaphragm driving mechanism 108 includes adriving mechanism for driving the diaphragm 106. The diaphragm drivingmechanism 108 drives the diaphragm 106 under the control of the CPU 1301in the system controller 130.

The shutter 110 allows the light receiving surface of the imagingelement 114 to be shielded from light or exposed to light. The shutter110 adjusts the exposure time of the imaging element 114. The shutterdriving mechanism 112 includes a driving mechanism for driving theshutter 110. The shutter driving mechanism 112 drives the shutter 110under the control of the CPU 1301 in the system controller 130.

The imaging element 114 includes the light receiving surface. The lightflux F from the subject focused via the photographic optical system 102is formed into an image on the light receiving surface of the imagingelement 114. The light receiving surface of the imaging element 114includes a plurality of two-dimensionally arranged pixels. A colorfilter is provided on the light entrance side of the light receivingsurface of the imaging element 114. The imaging element 114 converts thefigure (subject figure) corresponding to the light flux F formed intothe image on the light receiving surface to an electric signal(hereinafter referred to as an image signal) corresponding to the lightamount. Regarding the imaging element 114, imaging elements havingvarious configurations are known, such as a CCD type imaging element anda CMOS type imaging element. Regarding the color arrangement of thecolor filter, various arrangements such as a Bayer arrangement areknown. The present embodiment is not limited to a particularconfiguration of the imaging element 114 and can use imaging elementshaving various configurations.

The imaging element IF circuit 116 drives the imaging element 114 underthe control of the CPU 1301, and reads the image signal output by thedriving of the imaging element 114. The imaging element IF circuit 116subjects the image signal read from the imaging element 114 to analogprocessing such as correlated double sampling (CDS) processing andautomatic gain control (AGC) processing. The imaging element IF circuit116 converts the analog-processed image signal to a digital signal(hereinafter referred to as image data).

For example, a work area 118 a, a tracking image area 118 b, a trackingcolor log area 118 c, and a tracking data log area 118 d are formed anstorage areas in the SDRAM 118.

Data generated in each section of the imaging device 100 is temporarilystored in the work area 118 a. The data temporarily stored in the workarea 118 a is, for example, image data obtained by the imaging elementIF circuit 116.

Tracking image data is temporarily stored in the tracking image area 118b. The tracking image data is image data for a frame including atracking target subject in a tracking process.

A color information log for tracking the tracking target subject istemporarily stored in the tracking color log area 118 c.

A tracking data log is temporarily stored in the tracking data log area118 d. In the present embodiment, a plurality of tracking processes for,for example, the face of the subject, luminance information, and colorinformation are used to track the subject. Thus, tracking data used inthe tracking processes is temporarily stored in the tracking data logarea 118 d.

The display element 120 is, for example, a liquid crystal display (LCD).The display element 120 displays various images such as images for liveview, and image data recorded in the recording medium 128. The displayelement 120 will hereinafter be referred to as an LCD 120. The displayelement driving circuit 122 drives the LCD 120 in accordance with theimage data input under the control of the CPU 1301, and displays imageson the LCD 120.

The touch panel 124 is integrally provided on a display screen of theLCD 120. The touch panel 124 detects, for example, the contact (touch)of the finger of a user with the display screen of the LCD 120, andoutputs a contact detection signal including coordinates that indicatesthe touch position. The touch panel driving circuit 126 drives the touchpanel 124, and sends, to the CPU 1301, the contact detection signal fromthe touch panel 124. The CPU 1301 detects the user's contact operationon the display screen from the contact detection signal sent from thetouch panel 124, and performs processing corresponding to the contactoperation.

The recording medium 128 is, for example, a memory card. An image file128 a obtained by photography operation is recorded in the recordingmedium 128. The image file 128 a is formed by attaching a predeterminedheader to image data. For example, data indicating a photographycondition and data indicating a tracking position are recorded in theheader as tag data.

The system controller 130 controls the operation of the entire imagingdevice 100. The system controller 130 includes the CPU 1301; an AFcontrol circuit 1302 and an AE control circuit 1303 as various controlcircuits; an image processing circuit 1304; a ranging position settingcircuit 1305, a grouping setting circuit 1306, and a tracking featuredetection circuit 1307 as focus detection information acquiringcircuits; a tracking position setting circuit 1308 and a trackingcircuit 1309 as tracking processing circuits; a face detectionprocessing circuit 1310; a luminance tracking processing circuit 1311; acolor information tracking processing circuit 1312; and a memory controlcircuit 1313.

The CPU 1301 controls the operations of the focus adjustment mechanism104, the diaphragm driving mechanism 108, the shutter driving mechanism112, the display element driving circuit 122, and the touch paneldriving circuit 126, and also controls the operations of various controlcircuits inside the system controller 130.

The present device 100 includes a function to track the tracking targetby controlling the operation of the CPU 1301. The tracking functionincludes a plurality of focus detection areas C as shown in FIG. 21. Thetracking function tracks the subject A in accordance with each in-focusstate of each of the focus detection areas C regarding the trackingtarget subject A in the image data.

The AF control circuit 1302 controls a contrast AF process. Morespecifically, the AF control circuit 1302 extracts a high-frequencycomponent of the image data obtained by the imaging element IF circuit116, and accumulates the extracted high-frequency component to acquirean in-focus evaluation value for AF. The CPU 1301 evaluates the contrastof the image data in accordance with the in-focus evaluation value, andat the same time, controls the focus adjustment mechanism 104, therebyadjusting the focus lens of the photographic optical system 102 to anin-focus position.

The AE control circuit 1303 controls AE operation. More specifically,the AE control circuit 1303 calculates subject luminance by using theimage data obtained by the imaging element IF circuit 116. In accordancewith the subject luminance, the AE control circuit 1303 calculates, forexample, an opening amount (aperture value) of the diaphragm 106 duringexposure, and a release time (shutter speed value) of the shutter 110.

The image processing circuit 1304 performs various kinds of imageprocessing for the image data. The image processing includes, forexample, color correction processing, gamma (γ) correction processing,and compression processing. The image processing circuit 1304 alsoexpands compressed image data.

The focus detection information acquiring circuits include the rangingposition setting circuit 1305, the grouping setting circuit 1306, andthe tracking feature detection circuit 1307. The focus detectioninformation acquiring circuits acquire the in-focus state regarding thesubject A detected by the focus detection areas C shown in FIG. 21.

The ranging position setting circuit 1305 sets the focus detection areaC which is focused on the tracking target subject A among the focusdetection areas C. For example, as shown in FIG. 21, the rangingposition setting circuit 1305 detects the in-focus state regarding thesubject A in a plurality of focus detecting pixels in the focusdetection area C.

The grouping setting circuit 1306 groups the focus detection areas C setby the ranging position setting unit 1305 in accordance with thein-focus state. For example, if there are two sets of focus detectionareas C (shaded parts) which are focused on the subject A as shown inFIG. 2, the grouping setting circuit 1306 groups the sets of focusdetection areas C into focus detection area groups C1 and C2. Theformation of the focus detection area groups C1 and C2 means that thereare two subjects.

More specifically, when grouping, the grouping setting unit 1306 groups,as the same group, the focus detection areas which are adjacent to eachother and which have the same focal distance among the focus detectionareas C as shown in FIG. 3. For example, if the focus detection areas Caand Cb are adjacent to each other and have the same focal distance, thegrouping setting unit 1306 groups the focus detection areas Ca and Cb asthe same group.

The adjacent focus detection areas C are not exclusively the left andright focus detection areas Ca and Cb in the diagram of FIG. 3, and maybe the upper and lower focus detection areas Ca and Cc or may be theobliquely adjacent focus detection areas Ca and Cd.

When grouping, the grouping setting unit 1306 groups, into other groupssuch as the focus detection area groups C1 and C2, for example, thefocus detection area Ca, the focus detection area Ce located a presetnumber of pixels apart from the focus detection area Ca, and the focusdetection area Cf adjacent to the focus detection area Ce that have beenset by the ranging position setting unit 1305 as shown in FIG. 4.

The tracking feature detection circuit 1307 detects the feature amountof the tracking target subject A in, for example, the areas of the focusdetection area groups C1 and C2 grouped by the grouping setting unit1306. The tracking feature detection circuit 1307 detects the face of ahuman body, luminance, and color as the feature amount of the subject A.

The tracking position setting circuit 1308 sets, as a first trackingposition, the focus detection area C set by the ranging position settingunit 1308. The tracking position setting circuit 1308 sets, as a secondtracking position, the part having the feature amount detected by thetracking feature detection circuit 1307, that is, the part having theface of the human body, the luminance, and the color as the featureamount of the subject A.

The tracking circuit 1309 tracks (first tracking process) the trackingtarget subject A on moving images comprising a plurality of successiveframes in accordance with the first tracking position (focus detectionarea C) set by the tracking position setting unit 1308 depending on thenumber of groups set by the grouping setting unit 1306. Alternatively,the tracking circuit 1309 tracks (second tracking process) the trackingtarget subject A on moving images comprising a plurality of successiveframes in accordance with the second tracking position (part having theface, the luminance, and the color as the feature amount of the subjectA).

If the focus detection areas C are grouped into a plurality of groups,for example, the focus detection area groups C1 and C2 by the groupingsetting unit 1306, the tracking circuit 1309 selects the first trackingposition (focus detection area C) and the second tracking position (parthaving the face, the luminance, and the color as the feature amount ofthe subject A) in accordance with a positional relation between thesecond tracking position and the groups.

If no group is set by the grouping setting unit 1306, the trackingcircuit 1309 selects the second tracking position (part having the face,the luminance, and the color as the feature amount of the subject A).When one group is set, the tracking circuit 1309 selects the firsttracking position (focus detection area C). If a plurality of groups areset, the tracking circuit 1309 selects the first or second trackingposition from the second tracking position and the focus detection areasC which are in the in-focus state.

In the case of moving images comprising a plurality of successiveframes, the tracking circuit 1309 updates the first or second trackingposition for each of frame images to track the tracking target subject Aon a plurality of imaging data.

The face detection processing circuit 1310 detects the face of thesubject (person) in the image data, and tracks this face. In a facedetecting process, the amount of correlation between image data obtainedin each frame of the moving images and, for example, each of face parts402, 404, and 406 shown in FIG. 5A is found. The face part 402 is imagedata corresponding to a shade pattern around the nose of the person. Theface part 404 is image data corresponding to a shade pattern around theeyes of the person. The face part 406 is image data corresponding to ashade pattern around the mouth of the person. The amount of correlationbetween the image data and each of the face parts 402, 404, and 406 ismaximized at a predetermined arrangement that indicates the face of theperson shown in FIG. 5B. If each correlation amount is maximum, the faceis present in an area 408 including the face parts 402, 404, and 406.Although the face area is rectangular in the diagrams, the face area maybe circular.

The luminance tracking processing circuit 1311 tracks the subject A byusing the luminance information in the image data. In the trackingprocess that uses the luminance information, the image data of an (N−1)frame is stored in the SDRAM 118 as evaluation image data, for example,if the tracking target is set in the (N−1) frame shown in FIG. 6A. Theluminance tracking processing circuit 1311 sets the image data in apredetermined range 202 of the evaluation image data including thetracking target as standard image data (hereinafter, standard image data202). The luminance tracking processing circuit 1311 then searches thereference image data for a part corresponding to the standard image data202 included in the evaluation image data.

The tracking process of the N frame is described by way of example.First, the luminance tracking processing circuit 1311 stores the imagedata for the N frame in the SDRAM 118 as reference image data. Theluminance tracking processing circuit 1311 finds the amount ofcorrelation between image data in a predetermined search range 204 ofthe reference image data and the standard image data 202, and searchesthe image data in the predetermined search range 204 for a partcorresponding to the standard image data 202. The correlation amount isdetermined, for example, from a difference absolute value sum (theaccumulation of absolute values of luminance differences found for therespective pixels) between the standard image data and the referenceimage data.

For example, if the difference absolute value sum between the referenceimage data in an area 206 of the reference image data shown in FIG. 6Band the standard image data 202 is found, the area 206 of the referenceimage data and the standard image data 202 are obviously different imagedata, so that the difference absolute value sum is great. In contrast,if the difference absolute value sum between an area 208 of thereference image data and the standard image data 202 is found, thedifference absolute value sum is small. Thus, the difference absolutevalue sum is smaller if the amount of correlation between the referenceimage data and the standard image data 202 is greater.

In the tracking process that uses the luminance information, thereference image data is searched for an area having the maximumcorrelation amount, that is, the minimum difference absolute value sum.In the example shown in FIG. 6B, the area having the minimum differenceabsolute value sum is the area 208.

In the tracking position log area, a position having the highestcorrespondence in the area 208 is recorded as a tracking position. Ifthere are a plurality of positions to be recorded as tracking positions,for example, a position close to the center of the area 208 is used asthe tracking position. In the next tracking process, this trackingposition is preferably used as the start position of the trackingprocess. The time required for the tracking process can be reduced.

The color information tracking processing circuit 1312 tracks thesubject, for example, the face of the person in accordance with featureinformation, for example, the color information from the image dataacquired by the imaging in the imaging section 101. The colorinformation tracking processing circuit 1312 uses the color informationin the image data acquired by the imaging in the imaging section 101 toperform the tracking process of the face of the person.

The tracking process that uses the color information is brieflydescribed. In the tracking process that uses the color information, anarea determined to have the same color information as the colorinformation set in the evaluation image data, that is, a tracking colorarea is searched for.

For example, when a given position 302 of the subject is specified inthe (N−1) frame as shown in FIG. 7A, the color information trackingprocessing circuit 1312 acquires the color information at the position302 in the evaluation image data. The color information trackingprocessing circuit 1312 uses the position 302 as the start position ofthe tracking process to search for an area having the same colorinformation as the position 302.

More specifically, the color information tracking processing circuit1312 sequentially acquires the color information from the position 302as the start position to the periphery, and determines whether theacquired color information is the same as the color information at theposition 302. If the color information is determined to be the same asthe color information at the position 302, the color informationtracking processing circuit 1312 includes the position 302 in thetracking color area. If the acquired color information cannot bedetermined to be the same as the color information at the position 302,the color information tracking processing circuit 1312 does not includethe position 302 in the tracking color area.

As a result of searching for the tracking color area in this way, arectangular area 304 inscribed in the subject is the tracking colorarea, for example, when the subject has a single color as shown in FIG.7A. The tracking position to be recorded in the tracking position logarea is the same as, for example, the gravity center position of thetracking color area 304, for example, the position 302 shown in FIG. 7A.In the next tracking process, the tracking position (position 302) isused as the start position of the tracking process.

The tracking process of the N frame is shown by way of example. Thecolor information tracking processing circuit 1312 uses the trackingposition 302 of the (N−1) frame as the start position of the trackingprocess, in a predetermined search range of the image data of the Nframe stored as the reference image data shown in FIG. 7B. The colorinformation tracking processing circuit 1312 searches for areas whichcan be determined to have the same color information as the colorinformation in the tracking color area 304, as tracking color areassequentially from the periphery of the tracking position 302. In theexample shown in FIG. 7B, an area 306 is the tracking color area. Thecolor information tracking processing circuit 1312 sets a gravity centerposition 308 as a tracking position, and records this tracking position308 in the tracking position log area. In the tracking color area logarea, information (e.g. the positions of four corners) indicating therange of the tracking color area 306 is recorded.

The memory control circuit 1313 is an interface which is controlled, forexample, by the CPU 1301 to access the SDRAM 118, the recording medium128, and the flash ROM 134.

The camera operation switch 132 includes various operation members to beoperated by the user. For example, the camera operation switch 132includes a release button, a moving image button, a mode dial, aselection key, and a power supply button.

The release button includes a first release switch and a second releaseswitch. The first release switch is turned on when the release button ispressed halfway by the user. If the first release switch is turned on,photographic preparation operation such as an AF process is performed.The second release switch is turned on when the release button is fullypressed by the user. If the second release switch is turned on, exposureoperation for still image photography is performed.

The moving image button is an operation member for indicating the startor end of moving image photography. If the moving image button ispressed by the user, a moving image photography process is started. Ifthe moving image button is pressed during the execution of the movingimage photography process, the moving image photography process isended.

The mode dial is an operation member for selecting a photography settingof the imaging device. In the present embodiment, for example, a stillimage photography mode and a moving image photography mode can beselected as the photography setting of the imaging device. The stillimage photography mode is a photography setting for still imagephotography. The moving image photography mode is a photography settingfor moving image photography.

The selection key is an operation member for selecting or deciding anitem, for example, on a menu screen. If the selection key is operated bythe user, an item is selected or decided on the menu screen.

The power supply button is an operation member for turning on or off thepower supply of the present device 100. If the power supply button isoperated by the user, the present device 100 is activated and becomesoperable. If the power supply button is operated while the presentdevice is activated, the present device 100 is set to a power savingstandby state.

A program code for the CPU 1301 to perform various kinds of processingis stored in the flash ROM 134. Various control parameters are alsostored in the flash ROM 134, such as a photography operation flowchartof the present device 100, control parameters necessary for theoperations of the photographic optical system 102, the diaphragm 106,and the imaging element 114, and control parameters necessary for imageprocessing in the image processing circuit 1304. In the flash ROM 134,for example, data for face parts used in the face detection in the facedetection processing circuit 1310, and data for displaying a trackingframe are also stored.

Now, the photography operation of the present device having theabove-mentioned configuration is described with reference to aphotography operation flowchart shown in FIG. 8.

The CPU 1301 reads a necessary program code from the flash ROM 134 tocontrol the operation of the present device 100.

In step S100, the CPU 1301 determines whether the current photographysetting of the present device 100 is the still image photography mode orthe moving image photography mode. The photography setting is set by themode dial.

When the photography setting is determined to be the still imagephotography mode, the CPU 1301 starts a live view operation in stepS102. The live view operation is as follows. The CPU 1301 controls theshutter driving mechanism 112 to release the shutter 110, and thencontrols the imaging element IF circuit 116 to start the imaging by theimaging element 114. The CPU 1301 then inputs, to the image processingcircuit 1304, the image data which has been stored in the work area ofthe SDRAM 118 as a result of the imaging by the imaging element 114 sothat the image data is subjected to image processing for live viewdisplay. The CPU 1301 then inputs, to the display element drivingcircuit 122, the image data which has been subjected to the imageprocessing for the live view display, and displays an image on thedisplay element 120. The CPU 1301 displays moving images of the subjectby repeating the above-described display operation (live view display).The user can observe the subject by the moving image display.

In step S104, the CPU 1301 determines whether the first release switchhas been turned on. By performing this determination, the CPU 1301continues the live view operation until determining that the firstrelease switch has been turned on.

If it is determined that the first release switch has been turned on,the CPU 1301 performs a release AF process in step S106. In the releaseAF, the CPU 1301 drives the focus lens to an in-focus position by scandrive. That is, in the scan drive, the CPU 1301 controls the focusadjustment mechanism 104 to drive the focus lens in one direction withina predetermined scan range, and at the same time, evaluates in-focusevaluation values sequentially calculated by the AF control circuit1302. The CPU 1301 stops the driving of the focus lens at a lensposition where contrast is maximized as a result of the evaluation ofthe in-focus evaluation values. Such scan drive is performed when thereis a great difference between the position of the focus lens before AFand the in-focus position.

In step S108, the CPU 1301 controls the display element driving circuit122 to display a tracking frame W on the display element 120, forexample, as shown in FIG. 21. The tracking frame W is displayed at theposition of the tracking target subject A on the screen of the displayelement 120. For example, if the subject A brought into focus by therelease AF is set as a tracking target, the tracking frame W may bedisplayed on this subject A.

If the face of the subject A is detected by the face detectionprocessing circuit 1310, the tracking frame D1 may be displayed on theface, for example, as shown in FIG. 9 or FIG. 10. If the subject Adisplayed on the screen of the display element 120 is specified by thetouch panel 124, the tracking frame D1 may be displayed on the subjectA.

In step S110, the CPU 1301 performs a tracking process to track thesubject A.

In step S112, the CPU 1301 performs an AF process to focus on thesubject at the tracking position, and performs an AE process so that theexposure for the subject A at the tracking position will be proper. Inthe AF process after the tracking process, the focus lens is driven tothe in-focus position by the scan drive or wobbling drive. In thewobbling drive, the CPU 1301 determines whether the in-focus evaluationvalue calculated by the AF control circuit 1302 when the focus lens isdriven has increased as compared with the in-focus evaluation value atthe previous lens position.

If it is determined that the in-focus evaluation value has increased,the CPU 1301 slightly drives the focus lens in the same direction as theprevious direction. If the in-focus evaluation value has decreased, theCPU 1301 slightly drives the focus lens in a direction opposite to theprevious direction. The CPU 1301 rapidly repeats such operation togradually drive the focus lens to the in-focus position.

In the AE process, the CPU 1301 calculates an opening amount (aperturevalue) of the diaphragm 106 and a release time (shutter speed value) ofthe shutter 110 during this exposure so that the luminance of thesubject at the tracking position calculated by the AE control circuit1303 will reach a predetermined proper amount (proper exposure amount).

In step S114, the CPU 1301 determines whether the second release switchhas been turned on. If it is determined that the second release switchhas not been turned on, the CPU 1301 performs processes after thetracking process in step S110. If set to the still image photographymode, the CPU 1301 continues the tracking process until the secondrelease switch is turned on.

If the second release switch is turned on, the CPU 1301 controls thedisplay element driving circuit 122 so that a tracking frame D1 is notdisplayed, in step S116.

In step S118, the CPU 1301 performs a process to record still image datain the recording medium 128. During the recording process, the CPU 1301controls the shutter driving mechanism 112 to close the shutter 110. TheCPU 1301 then controls the diaphragm driving mechanism 108 to narrow thediaphragm 106 to the previously calculated aperture value. The CPU 1301then controls the shutter driving mechanism 112 to release the shutter110 for the previously calculated release time, and at the same time,performs the photography (exposure) by the imaging element 114.

The CPU 1301 processes, in the image processing circuit 1304, the stillimage data obtained via the imaging element 114. The CPU 1301 adds aheader to the still image data processed in the image processing circuit1304 to generate a still image file, and records the generated stillimage file in the recording medium 128.

In step S120, the CPU 1301 additionally writes data that indicates thetracking position obtained as a result of the tracking process in stepS110 in the still image file previously recorded in the recording medium128.

On the other hand, when the photography setting is determined to be themoving image photography mode in step S100, the CPU 1301 starts the liveview operation in step S122.

If it is determined that the moving image button which is an instructionto turn on the moving image photography has been turned on, the CPU 1301controls the display element driving circuit 122 in step S126 so thatthe tracking frame D1 is displayed over the face on the display element120, for example, as shown in FIG. 9 or FIG. 10.

In step S128, the CPU 1301 performs a tracking process to track thesubject A.

In step S130, the CPU 1301 instructs the AF control circuit 1302 toperform an AF process to bring the subject A at the tracking positioninto focus, and instructs the AE control circuit 1303 to perform an AEprocess so that the exposure for the subject A at the tracking positionwill be proper. In this AF process, the CPU 1301 drives the focus lensof the photographic optical system 102 to the in-focus position by thewobbling drive.

In step S132, the CPU 1301 performs a process to record moving imagedata in the recording medium 128. During the recording process, the CPU1301 controls the diaphragm driving mechanism 108 to narrow thediaphragm 106 to the aperture value calculated in the AE process. TheCPU 1301 then causes the imaging element 114 to perform imaging(exposure) for a time corresponding to the shutter speed valuecalculated in the AE process. After the end of the exposure, the CPU1301 generates a moving image file and records the moving image file inthe recording medium 128. The CPU 1301 processes, in the imageprocessing circuit 1304, the moving image data obtained via the imagingelement 114, and records, in the moving image file, the moving imagedata processed in the image processing circuit 1304.

In step S134, the CPU 1301 records data that indicates the trackingposition obtained as a result of the tracking process in step S128 inthe moving image file previously recorded in the recording medium 128.

In step S136, the CPU 1301 determines whether the moving image buttonhas been turned off. When it is determined that the moving image buttonhas not been turned off, the CPU 1301 performs processes after thetracking process in step S128.

Thus, in the moving image photography mode, the tracking process and therecording of the moving image data are continued until the moving imagebutton is turned off. If it is determined that the moving image buttonhas been turned off, the CPU 1301, in step S138, controls the displayelement driving circuit 122 so that the tracking frame D1 is notdisplayed.

Now, the tracking process is described with reference to a trackingprocess flowchart shown in FIG. 11.

In step S200, the CPU 1301 determines whether image data is the imagedata of the first frame where the tracking of the subject A is started.

If the frame is determined to be the first frame where the tracking isstarted, the CPU 1301 performs the release AF for a release AF in-focusarea AFE shown in FIG. 12 if the first release switch is turned on instep S202. In this release AF process, the CPU 1301 performs the scandrive to drive the focus lens to the in-focus position. The CPU 1301performs the release AF process, and stops the driving of the focus lensat the in-focus position regarding the subject A. The CPU 1301 updatesthe in-focus position regarding the subject A as standard focusinformation.

In step S204, the ranging position setting circuit 1305 updates thestandard focus detection areas C (shaded parts) as shown in FIG. 12 inthe release AF in-focus area AFE.

In step S206, the CPU 1301 causes the imaging element 114 to performimaging, and causes the imaging element IF circuit 116 to acquire frameimage data. In step S208, the CPU 1301 loads the frame image data intothe SDRAM 118.

In step S210, the CPU 1301 sets to perform the first tracking processfor the subject A in accordance with a focus detection area F set by theranging position setting circuit 1305, that is, in accordance with thefocus detection area F which is focused on the tracking target subject Aamong the focus detection areas C.

In step S212, the tracking feature detection circuit 1307 detects thefeature amount of the subject A for the second tracking process in, forexample, the areas of the focus detection area groups C1 and C2 groupedby the grouping setting circuit 1306. The tracking feature detectioncircuit 1307 detects the face of a human body, luminance, and color asthe feature amount of the subject A.

In step S214, the tracking feature detection circuit 1307 calculates atracking position of the subject A in accordance with the face of thehuman body, luminance, and color information as the feature amount ofthe subject A. FIG. 13 shows a luminance/color information tracking areaG1 in which the subject A is tracked in accordance with the luminanceand color information regarding the subject A.

In step S216, the CPU 1301 performs a priority tracking positiondetermination to determine whether to prioritize the first trackingprocess for the subject A in accordance with the focus detection area Fwhich is focused on the tracking target subject A or the second trackingprocess for the subject A in accordance with the face of the human body,luminance, and color as the feature amount of the subject A.

In step S218, the CPU 1301 determines the reliability of the firsttracking process or the second tracking process which has beendetermined as a result of the priority tracking position determination.In step S220, the CPU 1301 calculates a tracking position of the subjectA. In step S222, the CPU 1301 updates the position and size of thetracking frame W shown in FIG. 21.

Now, the operation of the first tracking process is described withreference to a first tracking process flowchart shown in FIG. 14A,14B.

In step S300, the grouping setting circuit 1306 initializes, to “0”, agroup number (No.) for grouping the focus detection areas C inaccordance with the in-focus state. For example, the grouping settingcircuit 1306 initializes, to “0”, the Group No. given to the focusdetection area groups C1 and C2 shown in FIG. 2.

In step S302, the ranging position setting circuit 1305 inputs imagesignals from all the focus detecting pixels in the imaging element 114,and acquires focus information regarding, for example, the in-focusstate regarding the subject A in all the focus detection areas C. Thefocus information makes it possible to determine whether or not thesubject A is in focus in each of the focus detection areas C, forexample, shown in FIG. 12.

In step S304, the grouping setting circuit 1306 sets an area number i ofthe focus detection areas C. The grouping setting circuit 1306 firstsets the area number i to “1”, and then repeats a loop “1”. In the loop“1”, whether to group each of the focus detection areas C (i=1, 2, 3, .. . , n) into the focus detection area group C1 or C2 is determined.

In step S306, the grouping setting circuit 1306 finds an absolute valueof a difference between the focus information regarding the focusdetection areas C and standard focus information as shown in Equation(1), and determines whether this absolute value is less than a presetthreshold.|Focus information regarding focus detection areas C−standard focusinformation|<threshold  (1)

If it is determined that the absolute value of the difference betweenthe focus information regarding the focus detection areas C and thestandard focus information is less than the threshold, the groupingsetting circuit 1306 determines in step S308 whether the area number iof the focus detection areas C is “0”.

If it is determined that the area number i of the focus detection areasC is not “0”, that is, the area number i is “1”, the grouping settingcircuit 1306 moves to a loop “2” in step S310.

In the loop “2”, the grouping setting circuit 1306 sets the focusdetection area Group No. to J(=1).

In step S312, the grouping setting circuit 1306 determines whether thefocus detection area C is in the same group as the focus detection areagroup No. J(=1). In this determination, it is found out whether thedetermination target focus detection area C is adjacent to the focusdetection area C of the focus detection area group No. J(=1).

If it is determined that the focus detection area C is adjacent, thegrouping setting circuit 1306 adds the determination target focusdetection area C as the focus detection area which is in the same groupas the focus detection area group No. J(=1) in step S314.

If it is determined that the focus detection area C is not adjacent, thegrouping setting circuit 1306 does not add the determination targetfocus detection area C as the focus detection area which is in the samegroup as the focus detection area group No. J(=1). The grouping settingcircuit 1306 repeats steps S312 and S314, and determines the adjacentfocus detection areas C in the same group for each of the focusdetection area groups No. J(=1, 2, 3, . . . , m).

In step S318, the grouping setting circuit 1306 determines whether thedetermination target focus detection area C is adjacent to a pluralityof focus detection area groups, for example, the groups No. J(=1, 2, 3).

If it is determined that the determination target focus detection area Cis adjacent to a plurality of focus detection area groups, the groupingsetting circuit 1306 integrates the adjacent focus detection areagroups, for example, the groups No. J(=1, 2, 3) into one group No. J(=1)in step S320.

In step S322, the grouping setting circuit 1306 modifies the group No. Jin accordance with Equation (2).Group No. J=group No. J−number of adjacent Groups−1  (2)

In step S324, the grouping setting circuit 1306 determines whether thereis any focus detection area group No. J to which the determinationtarget focus detection area C is adjacent.

If it is determined that there is no adjacent focus detection area groupNo. J, the grouping setting circuit 1306 increments the focus detectionarea group No. J in step S326. In step S328, the grouping settingcircuit 1306 adds the focus detection areas C (i=1, 2, 3, . . . , n) tothe focus detection area group No. J.

In step S330, the grouping setting circuit 1306 repeats the above loop“1”.

In step S332, the grouping setting circuit 1306 searches for a focusdetection area group No. J that includes the standard focus detectionareas C.

As a result of the search, the grouping setting circuit 1306 determinesin step S334 whether there is any focus detection area group No. J thatincludes the standard focus detection areas C.

If it is determined that there is a focus detection area group No. Jthat includes the standard focus detection areas C, the grouping settingcircuit 1306 sets the focus detection area group No. J that includes thestandard focus detection areas C as the first tracking position in stepS336.

On the other hand, if there is no focus detection area group No. J thatincludes the standard focus detection areas C, the grouping settingcircuit 1306 sets all the focus detection area groups No. J as the firsttracking positions in step S338.

As described above, if the focus detection areas, for example, the focusdetection areas Ca and Cb are adjacent to each other and have the samefocal distance among a plurality of focus detection areas C as shown inFIG. 3, the grouping setting circuit 1306 groups these focus detectionareas Ca and Cb as the same group.

The adjacent focus detection areas C are not exclusively the left andright focus detection areas Ca and Cb in the diagram of FIG. 3, and maybe the upper and lower focus detection areas Ca and Cc or may be theobliquely adjacent focus detection areas Ca and Cd.

The grouping setting circuit 1306 searches for the focus detection areaCe and this focus detection area Ce located a preset number of pixelsapart from, for example, the focus detection area Ca set by the rangingposition setting circuit 1305 as shown in FIG. 4. The grouping settingcircuit 1306 groups the focus detection area Ce and the focus detectionarea Cf adjacent to the focus detection area Ce into other groups suchas the focus detection area groups C1 and C2.

Now, the operation of the priority tracking position determination isdescribed with reference to a priority tracking position determinationflowchart shown in FIG. 15.

The tracking circuit 1309 tracks the tracking target subject A inaccordance with the first tracking position (focus detection area C) setby the tracking position setting circuit 1308 depending on the number ofgroups set by the grouping setting circuit 1306, or in accordance withthe second tracking position (part having the face, the luminance, andthe color as the feature amount of the subject A).

More specifically, in step S400, the tracking circuit 1309 determineswhether the number of groups at the first tracking position (focusdetection area C) is “0”, “1”, or “2 or more”.

If it is determined that the number of groups at the first trackingposition (focus detection area C) is “0”, the tracking circuit 1309selects the second tracking position (part having the face, theluminance, and the color as the feature amount of the subject A) in stepS404, and sets the second tracking position as the tracking position.

If it is determined that the number of groups at the first trackingposition (focus detection area C) is “1”, the tracking circuit 1309selects the first tracking position (focus detection area C) in stepS406, and sets the first tracking position as the tracking position. Forexample, FIG. 16 shows the composition of the subject A having one focusdetection area group C1.

In step S412, the tracking circuit 1309 updates the standard focusinformation in accordance with the focus information regarding the firsttracking position (focus detection area C).

In step S414, the tracking circuit 1309 updates the standard focusdetection areas C in accordance with the focus information regarding thefirst tracking position (focus detection area C).

In step S416, the tracking circuit 1309 corrects the second trackingposition (part having the face, the luminance, and the color as thefeature amount of the subject A) in accordance with the first trackingposition (focus detection area C).

If it is determined that the number of groups at the first trackingposition (focus detection area C) is “2 or more”, the tracking circuit1309 determines in step S402 whether the focus detection area groups C1and C2 that include the second tracking position (part having the face,the luminance, and the color as the feature amount of the subject A)exit. For example, FIG. 17 shows a composition in which two subjects Aand E are located close to each other. FIG. 18 shows a composition inwhich the two subjects A and E are located apart from each other. Thetwo subjects A and E that are located apart from each other correspondto having two focus detection area groups C1 and C2, that is, two ormore groups.

If it is determined that the focus detection area groups C1 and C2 thatinclude the second tracking position exist, the tracking circuit 1309sets the focus detection area groups C1 and C2 that include the secondtracking position as the first tracking position (focus detection areaC) in step S408, updates the standard focus detection areas C inaccordance with the focus information regarding the first trackingposition, and moves to step S412.

On the other hand, if the focus detection area groups C1 and C2 thatinclude the second tracking position do not exist, the tracking circuit1309 updates the standard focus detection areas C in accordance with thesecond tracking position (part having the face, the luminance, and thecolor as the feature amount of the subject A) in step S410.

In this way, according to the first embodiment, the focus detection areaC which is focused on the subject A is set among the focus detectionareas C. The focus detection areas C are grouped in accordance with thein-focus state. The feature amount of the subject A in the areas of thefocus detection area groups C1 and C2 is detected. The focus detectionarea C which is in the in-focus state is set as the first trackingposition, or a part having the feature amount of the subject A is set asthe second tracking position. The subject A is tracked in accordancewith the first or second tracking position depending on the number ofthe focus detection area groups C1 and C2. Consequently, according tothe first embodiment, even if the additional subject E exists in thevicinity of or adjacent to the subject A, the tracking target subject Acan be reliably tracked and the reliability can be improved without atransfer from the subject A to the additional subject E.

If the focus detection areas C are grouped as the focus detection areagroup, the second tracking position is selected if there is no focusdetection area group. If there is one group, the first tracking positionis selected. If there are two or more groups, the first or secondtracking position is selected from the second tracking position and thefocus detection areas C which are in the in-focus state. Thus, forexample, even if the two subjects A and E that have been located closeto each other as shown in FIG. 17 come apart as shown in FIG. 18, thetracking target does not transfer from the subject A to the subject E,and the subject A can be kept tracked as the tracking target.

If a vehicle H comes into a composition for photographing the subject Aas an additional subject as shown in FIG. 19, the tracking featuredetection circuit 1307 calculates a tracking position of the vehicle Hin accordance with luminance and color information as the feature amountof the vehicle H, and sets a luminance/color information tracking areaG2 to track the vehicle H in accordance with the luminance and the colorinformation.

The subject A and the vehicle H are included as shown in FIG. 19 if thenumber of groups at the first tracking position (focus detection area C)is “2 or more” as the focus detection area groups C1 and C2, forexample, as shown in FIG. 18 and when the second tracking position ofthe vehicle H (part having the face, the luminance, and the color as thefeature amount of the vehicle H) is not included in the focus detectionarea group C1 of the subject A in the case shown in FIG. 19.

The tracking circuit 1309 sets the focus detection area group C1including the second tracking position as shown in FIG. 20 as the firsttracking position (focus detection area C), and updates the standardfocus detection areas C in accordance with the focus informationregarding the first tracking position.

Therefore, even if the vehicle H comes into the composition forphotographing the subject A, the tracking target does not transfer fromthe subject A to the subject E, and the subject A can be kept tracked asthe tracking target.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A tracking apparatus comprising: a group settingcircuit which groups a plurality of focus detection areas in image dataincluding a tracking target; a feature detection circuit which detects afeature amount of the tracking target in areas of one or more of theplurality groups grouped by the group setting circuit; a trackingcircuit which: sets the focus detection area focused on the trackingtarget as a first tracking position, sets an area having the featureamount detected by the feature detection circuit as a second trackingposition, performs a priority tracking position determination to set thefirst tracking position or the second tracking position as a prioritytracking position based on the number of groups set by the group settingcircuit, and tracks the tracking target in accordance with the first orsecond tracking position based on the priority tracking positiondetermination; a display circuit which displays an image based on theimage data and a tracking frame indicative of a position of the trackingtarget; and a control circuit which provides, when the image data isrecorded as a still image, an instruction not to display the trackingframe after an instruction for still image photography and thereafterrecords a still image file based on the image data in a recording mediumtogether with a position of the tracking target, and records, when theimage data is recorded as a moving image, a moving image file based onthe image data in a recording medium, successively records a position ofthe tracking target in a recording medium, and provides an instructionnot to display the tracking frame after an instruction to end movingimage photography.
 2. The tracking apparatus of claim 1, wherein thetracking circuit performs the priority tracking position determinationin accordance with a focus state of the focus detection areas.
 3. Thetracking apparatus of claim 1, wherein the group setting circuit groupsthe plurality of focus detection areas in accordance with a focus stateamong the focus detection areas in image data including a trackingtarget.
 4. The tracking apparatus of claim 1, wherein the group settingcircuit groups the plurality of focus detection areas in accordance witha difference between focus information regarding the focus detectionareas and standard focus information.
 5. The tracking apparatus of claim4, wherein when the group setting circuit groups the plurality of focusdetection areas based on whether the difference between the focusinformation regarding the focus detection areas is less than athreshold.
 6. The tracking apparatus of claim 1, wherein the trackingcircuit sets the second tracking position as the priority trackingposition when there are no groups set by the group setting circuit. 7.The tracking apparatus of claim 1, wherein the tracking circuit sets thefirst tracking position as the priority tracking position when one groupis set by the group setting circuit.
 8. The tracking apparatus of claim1, wherein the tracking circuit sets the first tracking position as thepriority tracking position when two or more groups are set by the groupsetting circuit and the groups include a group including the secondtracking position.
 9. The tracking apparatus of claim 1, wherein thetracking circuit sets the second tracking position as the prioritytracking position when two or more groups are set by the group settingcircuit and none of the groups include the second tracking position. 10.The tracking apparatus according to claim 1, wherein the image dataincludes a plurality of successive frame images, and the trackingcircuit updates the first or second tracking position for each of thesuccessive frame images to track the tracking target.
 11. A trackingsystem comprising: an imaging device which obtains image data; a groupsetting circuit which groups a plurality of focus detection areas in theimage data including a tracking target; a feature detection circuitwhich detects a feature amount of the tracking target in areas of one ormore of the plurality groups grouped by the group setting circuit; atracking circuit which: sets the focus detection area focused on thetracking target as a first tracking position, sets an area having thefeature amount detected by the feature detection circuit as a secondtracking position, performs a priority tracking position determinationto set the first tracking position or the second tracking position as apriority tracking position based on the number of groups set by thegroup setting circuit, and tracks the tracking target in accordance withthe first or second tracking position based on the priority trackingposition determination; a display circuit which displays an image basedon the image data and a tracking frame indicative of a position of thetracking target; and a control circuit which provides, when the imagedata is recorded as a still image, an instruction not to display thetracking frame after an instruction for still image photography andthereafter records a still image file based on the image data in arecording medium together with a position of the tracking target, andrecords, when the image data is recorded as a moving image, a movingimage file based on the image data in a recording medium, successivelyrecords a position of the tracking target in a recording medium, andprovides an instruction not to display the tracking frame after aninstruction to end moving image photography.
 12. The tracking system ofclaim 11, wherein the tracking circuit sets the second tracking positionas the priority tracking position when there are no groups set by thegroup setting circuit.
 13. The tracking system of claim 11, wherein thetracking circuit sets the first tracking position as the prioritytracking position when one group is set by the group setting circuit.14. The tracking system of claim 11, wherein the tracking circuit setsthe first tracking position as the priority tracking position when twoor more groups are set by the group setting circuit and the groupsinclude a group including the second tracking position.
 15. The trackingsystem of claim 11, wherein the tracking circuit sets the secondtracking position as the priority tracking position when two or moregroups are set by the group setting circuit and none of the groupsinclude the second tracking position.
 16. A tracking method comprising:obtaining image data using an imaging device; grouping a plurality offocus detection areas in the image data including a tracking target;detecting a feature amount of the tracking target in areas of one ormore of the plurality groups; setting the focus detection area focusedon the tracking target as a first tracking position, setting an areahaving the detected feature amount as a second tracking position,performing a priority tracking position determination to set the firsttracking position or the second tracking position as a priority trackingposition based on the set number of groups, tracking the tracking targetin accordance with the first or second tracking position based on thepriority tracking position determination; displaying an image based onthe image data and a tracking frame indicative of a position of thetracking target; providing, when the image data is recorded as a stillimage, an instruction not to display the tracking frame after aninstruction for still image photography and thereafter recording a stillimage file based on the image data in a recording medium together with aposition of the tracking target, and recording, when the image data isrecorded as a moving image, a moving image file based on the image datain a recording medium, successively recording a position of the trackingtarget in a recording medium, and providing an instruction not todisplay the tracking frame after an instruction to end moving imagephotography.
 17. The tracking method of claim 16, wherein the secondtracking position is set as the priority tracking position when thereare no set groups.
 18. The tracking method of claim 16, wherein thefirst tracking position is set as the priority tracking position whenthere is one set group.
 19. The tracking method of claim 16, wherein thefirst tracking position is set as the priority tracking position whenthere are two or more set groups and the groups include a groupincluding the second tracking position.
 20. The tracking method of claim16, wherein the second tracking position is set as the priority trackingposition when there are two or more set groups and none of the groupsinclude the second tracking position.
 21. The tracking apparatus ofclaim 1, wherein the tracking circuit: sets the second tracking positionto the position of the tracking target when there are no groups set bythe group setting circuit, sets the first tracking position to theposition of the tracking target and updates a standard area to the firsttracking position when one group is set by the group setting circuit;sets the first tracking position included in the second trackingposition to the position of the tracking target and updates the standardarea to the first tracking position included in the second trackingposition when two or more groups are set by the group setting circuitand the groups include a group including the second tracking position,and sets the second tracking position to the position of the trackingtarget and updates the standard area to the second tracking positionwhen two or more groups are set by the group setting circuit and none ofthe groups include the second tracking position.